首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   23039篇
  免费   812篇
  国内免费   326篇
电工技术   486篇
综合类   657篇
化学工业   4444篇
金属工艺   1323篇
机械仪表   911篇
建筑科学   733篇
矿业工程   336篇
能源动力   429篇
轻工业   1332篇
水利工程   456篇
石油天然气   1486篇
武器工业   87篇
无线电   1240篇
一般工业技术   5251篇
冶金工业   2239篇
原子能技术   928篇
自动化技术   1839篇
  2022年   284篇
  2021年   460篇
  2020年   386篇
  2019年   419篇
  2018年   592篇
  2017年   608篇
  2016年   637篇
  2015年   594篇
  2014年   733篇
  2013年   1165篇
  2012年   859篇
  2011年   925篇
  2010年   802篇
  2009年   802篇
  2008年   715篇
  2007年   712篇
  2006年   562篇
  2005年   480篇
  2004年   480篇
  2003年   530篇
  2002年   701篇
  2001年   621篇
  2000年   364篇
  1999年   229篇
  1990年   215篇
  1989年   248篇
  1988年   232篇
  1987年   234篇
  1986年   253篇
  1985年   267篇
  1984年   291篇
  1983年   271篇
  1982年   262篇
  1981年   262篇
  1980年   266篇
  1979年   287篇
  1978年   360篇
  1977年   336篇
  1976年   353篇
  1975年   333篇
  1974年   400篇
  1973年   377篇
  1972年   358篇
  1971年   331篇
  1970年   281篇
  1969年   277篇
  1968年   268篇
  1967年   250篇
  1966年   216篇
  1965年   213篇
排序方式: 共有10000条查询结果,搜索用时 109 毫秒
121.
Results of a study are reported on the utilization of ground vulcanizate, which is a waste product of rubber prcoessing plants. Loaded stocks of various commercial rubbers act as objects for the study. Talc, kaolin, silicon dioxide, and furnace carbon black are used as fillers. According to the results of a study on the effect of the amount of rubber crumb, an increase in the content of unmodified crumb leads to a decrease in tear resistance that is associated with poor wettability. To increase wettability, we use organosilicon couplings. It is shown that the addition of vulcanizate to rubber stocks, together with highly dispersed fillers treated with organosilicon couplings, leads to a significant increase in tear resistance and makes it possible to significantly reduce the cost of production and utilization.  相似文献   
122.
A unit for making L-class high-strength pump-compressor tubing composed of low-carbon, low-alloy steels of type 15GFB is now being used on the 140 mill in the tube-rolling shop at the Rustavi Metallurgical Plant. The steel 15GFB pump-compressor tubing made by the technology that was developed has the following service properties: σy = 630–670 N/mm2, σu = 730–780 N/mm2, δ = 18–22%, ψ = 55–60%, KCU = 1.6–2.2 MJ/m2. The percentage of ductile fracture at room temperature is 85–95%. __________ Translated from Metallurg, No. 1, pp. 79–80, January, 2006.  相似文献   
123.
124.
Correlations between each of two parameters of empirical relationships describing arrays of experimental data on the long-term strength, creep, multi- and low-cycle fatigue, and the growth of fatigue cracks are established. Well-defined relationships between parameters within each array make it possible to reduce significantly the required volume of material tests. The physical essence of the observed correlations is associated with the thermally active nature of damage processes, which accompany each form of material tests. It is demonstrated that the pattern of the dependence of correlating empirical parameters on fundamental characteristics of thermally activated damage processes can be established for all types of tests under consideration: the height of the potential barrier, the frequency factor, etc. For all types of tests, analytical predictions are in good qualitative agreement with correlations observed in experiment.Translated from Problemy Prochnosti, No. 6, pp. 3–9, June, 1994.  相似文献   
125.
A measurement and computing system designed for acoustical investigations of liquid crystals, magnetic fluids, etc., in the frequency range 0.15–1.2 MHz is described.Translated from Izmeritel'naya Tekhnika, No. 2, pp. 51–53, February, 1994.  相似文献   
126.
J. excelsa , J. foetidissima and J. oxycedrus. Among the compounds the monoterpenes exist in minor amounts while the sesquiterpenes including their oxygenated members as well as sesquiterpene alcohols consist of the majority of the whole substances. The existence of some compounds of the oils might be attributes of the species and their sap- and heartwood. On the other side though notable differences, the essential oils of Turkish juniper woods resemble the commercial cedar wood oils.
Die Zusammensetzung der flüchtigen Extraktstoffe im Holz von Juniperus foetidissima und Juniperus oxycedrus
J. excelsa , J. foetidissima und J. oxycedrus. Monoterpene bilden einen geringen Anteil der Extraktstoffe. Der Hauptteil besteht aus Sesquiterpenen mit deren Oxydationsprodukten. Das Vorkommen einiger der ?le k?nnte charakteristisch sein für die jeweilige Art bzw. deren Splint- und Kernholz Allerdings gleichen diese ?le, trotz geringer Unterschiede, den wesentlichen ?lbestandteilen von Kommerziellen Zedernh?lzern.


This work was supported by the research found of the Istanbul University. Project nr: 1335/280799.  相似文献   
127.
报道了废塑料炼油工艺中连续法、间歇法、半连续法等各种方法的特点 ;重点对各工业化流程中存在的问题和解决的方法进行了讨论 ,并提出了一些合理化的建议。  相似文献   
128.
Experiments were performed for comparative assessment of the effect of ionizing radiation on the service characteristics of 30% TBP solutions in various diluents: hexachlorobutadiene (HCBD), mixtures of n-paraffins (RED diluent), and fraction of naphthenic hydrocarbons (RZh diluent). The following main parameters were chosen for comparative assessment of the quality of irradiated extractant solutions: composition and behavior of diluent radiolysis products, effect of diluents on the TBP radiolysis, and aggregative stability of emulsions in the main operations of the extraction cycle. The service life of the extraction mixtures was estimated from variation of the above parameters with the irradiation dose. Principles for choosing solvents with increased service life under irradiation were substantiated.  相似文献   
129.
An inductive power-amplifier stage based on a two-coil assembly and two electrically exploded conductors used as circuit breakers is described. Owing to the magnetic flux conservation, the interruption of the current in the first of the storage coils causes an increase of the current in the second coil, which results in a rapid thermal burst of the second electrically exploded conductor. As a result, the load-current rise-time is 20 times less than the charging-current rise time and the amplitude of the current increases.  相似文献   
130.
We study analytically and numerically the interaction of vortices in current-carrying narrow superconducting strips. The characteristic time of vortex-antivortex pair annihilation and the energetic losses in the strip are evaluated as a function of the external transport current and width of the strip. The effects of an external magnetic field on the motion of a single vortex are discussed.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号